1. Field of the Invention
The present invention relates to a powdered base material treated with organic silicon compounds, a method for producing a powdered base material treated with organic silicon compounds, and a cosmetic comprising the powdered base material treated with organic silicon compounds. The powdered base material treated with organic silicon compounds according to the present invention can be used as additives for resins, paints, and the like, in addition to cosmetics.
2. Description of the Related Art
Heretofore, a pigment surface-treated with an organic silicon compound, such as methyl hydrogen polysiloxane, is excellent in repellence, and is recently used extensively in two-way cake type cosmetic or powdered foundation for the purpose mainly of preventing makeup collapsing.
In JP Patent Kokai Publication JP-A-7-196946 is disclosed a pigment treated with an organic silicon compound in which a straight-chain reactive alkyl polysiloxane has been adsorbed with orientation under heating treatment to a pigment in the surface, and in which the reactive alkyl polysiloxane is a straight-chain reactive alkyl polysiloxane having a polymerization degree of 25 to 100 and a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 1.0 to 1.3, with one of the terminals of the molecular chain carrying at least one of an alkoxy group, a hydroxy group, a halogen atom, an amino group, and an imino group.
1. Problem to be Solved by the Invention
In the course of the completion to the present invention, the following problems have been also found by the present invention.
The pigment treated with the organic silicon compound, such as methyl hydrogen polysiloxane, suffers from the following problems:
It is noted that the conventional methyl hydrogen polysiloxane, such as KF99 manufactured by SHIN-ETSU KAGAKU KOGYO KK, TSF484 manufactured by TOSHIBA SILICONE KK or SH1107 manufactured by TORAY DOW-CORNING KK, undergo cross-linking polymerization reaction, and that, since methyl hydrogen polysiloxane which has covered the surface of the powdered pigment assumes a reticulate three-dimensional structure, it is progressively converted to resin, thus generating a sole silicone resin, or causing granulation or flocculation of the powdered pigment particles. Thus, the conventional pigment treated with the organic silicon compound has a rough or coarse feeling in use. EQU (CH.sub.3).sub.3 SiO(CH.sub.3 HSiO).sub.n Si(CH.sub.3).sub.3 (4)
wherein n is an integer of 30 to 40.
On the other hand, the structure of routinely employed methyl hydrogen polysiloxane is as shown in the above general formula (4). Since methyl hydrogen polysiloxane having this structure has a functional group in each siloxane unit, it is subject to steric hindrances on thermal polymerization to render the progress of the reaction difficult. Thus, a large quantity of non-reacted hydrogen atoms are left in the methyl hydrogen polysiloxane molecules.
If the powdered pigment surface-treated with this methyl hydrogen polysiloxane is mixed into a cosmetic, residual hydrogen is produced by alkaline materials contained in the cosmetic to give rise to such phenomenon in which, in the case of an emulsified product, the vessel for the cosmetic tends to be expanded or destroyed and, in the case of a powdered article, above all pressed goods, the solidified state is embrittled and crushed to pieces. Also, in the manufacturing process for the cosmetic, a residual hydrogen gas tends to be yielded under alkaline or acidic conditions thus causing the risk of explosion during manufacture or causing a safety problem to the user.
Moreover, since the main skeleton is comprised of methyl hydrogen siloxane, the main chain has a decreasing degree of freedom with progress in polymerization, such that the produced coating is hard and brittle while tending to be cracked. Thus, the pigment treated with the organic silicon compound, obtained upon coating the powdered pigment with this methyl hydrogen polysiloxane followed by polymerization, experiences a problem of lowered crushing strength or lowered water-proof properties due to the low crushing strength and the high rate of coating destruction.
The pigment treated with the organic silicon compound, in which the above-mentioned specified straight-chain reactive alkyl polysiloxane is oriented and adsorbed to the pigment surface by heat processing, as disclosed in JP Patent Kokai Publication JP-A-7-196946, overcomes the above-mentioned problem. That is, with the pigment treated with the organic silicon compound described in the above publication, as contrasted with the pigment in which methyl hydrogen polysiloxane has undergone cross-linking polymerization reaction to form a resin film as described above, the above-mentioned specified reactive alkyl polysiloxane coated on the surface of the powdered cosmetic is heated and thereby the straight-chain alkyl polysiloxane is present affixed to the powdered pigments in the oily state, there is therefore no risk of flocculation of the particles of the powdered pigments, thus assuring excellent feeling to the touch, adhesion to skin and good color extension.
However, it has not been possible with the pigment treated with the organic silicon compound, obtained on heating with the above-mentioned specified reactive alkyl polysiloxane, to realize optimum hydrophobic properties or water-proofness for starting materials for the cosmetic, in particular for pearl pigments such as hydrated yellow iron oxide, iron oxide, titanium oxide or titanium mica.
The fact that the pigment treated with the organic silicon compound, obtained on reacting with the specified reactive alkyl polysiloxane, as described in the above-mentioned publication, is not sufficient in hydrophobic properties or in water-proofness, is manifested particularly significantly when the pigment treated with the organic silicon compound is mixed into an emulsion of emulsion-type cosmetic, such as cream foundation or liquid foundation. Specifically, in the emulsion type cosmetic, the above-mentioned pigment exhibiting the relatively strong adhesion properties of the reactive alkyl polysiloxane shifts to the oily phase, while the pigment exhibiting relatively weak adhesion shifts to the aqueous phase, thus leading to color separation or separation of the cream foundation or li quid foundation to cause problem, in particular, in the emulsion type foundation of cosmetic.
It is therefore an object of the present invention to overcome the above-mentioned problems of the related arts, and to provide a powdered base material treated with an organic silicon compound exhibiting superior adhesion to the skin and particularly smooth feeling to the touch, free of flocculation, exhibiting color hue ( tone ) of extremely high saturation (good color extension properties) when combined with a colored pigment, and which is superior in hydrophobic properties and water-proofness, without loss of the desirable characteristics of freedom from residual hydrogen, high safety and high quality when used in conjunction with colored pigments. It is another object of the present invention to provide a method for producing the powdered base material and the cosmetic containing the powdered base material treated with an organic silicon compound.